mirror of https://github.com/mkerrisk/man-pages
malloc_info.3: New page for malloc_info(3)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
parent
35af1345a1
commit
47c3118377
|
@ -0,0 +1,251 @@
|
|||
.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
|
||||
.\"
|
||||
.\" Permission is granted to make and distribute verbatim copies of this
|
||||
.\" manual provided the copyright notice and this permission notice are
|
||||
.\" preserved on all copies.
|
||||
.\"
|
||||
.\" Permission is granted to copy and distribute modified versions of this
|
||||
.\" manual under the conditions for verbatim copying, provided that the
|
||||
.\" entire resulting derived work is distributed under the terms of a
|
||||
.\" permission notice identical to this one.
|
||||
.\"
|
||||
.\" Since the Linux kernel and libraries are constantly changing, this
|
||||
.\" manual page may be incorrect or out-of-date. The author(s) assume no
|
||||
.\" responsibility for errors or omissions, or for damages resulting from
|
||||
.\" the use of the information contained herein. The author(s) may not
|
||||
.\" have taken the same level of care in the production of this manual,
|
||||
.\" which is licensed free of charge, as they might when working
|
||||
.\" professionally.
|
||||
.\"
|
||||
.\" Formatted or processed versions of this manual, if unaccompanied by
|
||||
.\" the source, must acknowledge the copyright and authors of this work.
|
||||
.\"
|
||||
.TH MALLOC_INFO 3 2012-04-28 "GNU" "Linux Programmer's Manual"
|
||||
.SH NAME
|
||||
malloc_info \- export malloc state to a stream
|
||||
.SH SYNOPSIS
|
||||
.nf
|
||||
.B #include <malloc.h>
|
||||
.sp
|
||||
.BI "int malloc_info(int " options ", FILE *" fp );
|
||||
.fi
|
||||
.SH DESCRIPTION
|
||||
The
|
||||
.BR malloc_info ()
|
||||
function exports an XML string that describes the current state
|
||||
of the memory-allocation
|
||||
implementation in the caller.
|
||||
The string is printed on the file stream
|
||||
.IR fp .
|
||||
The exported string includes information about all arenas (see
|
||||
.BR malloc (3)).
|
||||
|
||||
As currently implemented,
|
||||
.I options
|
||||
must be zero.
|
||||
.SH RETURN VALUE
|
||||
On success,
|
||||
.BR malloc_info ()
|
||||
returns 0;
|
||||
on error, it returns \-1.
|
||||
.SH ERRORS
|
||||
.TP
|
||||
.B EINVAL
|
||||
.I options
|
||||
was nonzero.
|
||||
.SH VERSIONS
|
||||
.BR malloc_info (3)
|
||||
was added to glibc in version 2.10.
|
||||
.SH CONFORMING TO
|
||||
This function is a GNU extension.
|
||||
.SH NOTES
|
||||
The memory-allocation information is provided as an XML string
|
||||
(rather than a C structure)
|
||||
because the information may change over time
|
||||
(according to changes in the underlying implementation).
|
||||
The output XML string includes a version field.
|
||||
|
||||
The
|
||||
.BR malloc_info ()
|
||||
function is designed to address deficiencies in
|
||||
.BR malloc_stats (3)
|
||||
and
|
||||
.BR mallinfo (3).
|
||||
.SH EXAMPLE
|
||||
The program below takes up to four command-line arguments,
|
||||
of which the first three are mandatory.
|
||||
The first argument specifies the number of threads that
|
||||
the program should create.
|
||||
All of the threads, including the main thread,
|
||||
allocate the number of blocks of memory specified by the second argument.
|
||||
The third argument controls the size of the blocks to be allocated.
|
||||
The main thread creates blocks of this size,
|
||||
the second thread created by the program allocates blocks of twice this size,
|
||||
the third thread allocates blocks of three times this size, and so on.
|
||||
|
||||
The program calls
|
||||
.BR malloc_info ()
|
||||
twice to display the memory-allocation state.
|
||||
The first call takes place before any threads
|
||||
are created or memory allocated.
|
||||
The second call is performed after all threads have allocated memory.
|
||||
|
||||
In the following example,
|
||||
the command-line arguments specify the creation of one additional thread,
|
||||
and both the main thread and the additional thread
|
||||
allocate 10000 blocks of memory.
|
||||
After the blocks of memory have been allocated,
|
||||
.BR malloc_info ()
|
||||
shows the state of two allocation arenas.
|
||||
.in +4
|
||||
.nf
|
||||
|
||||
.RB "$ " "getconf GNU_LIBC_VERSION"
|
||||
glibc 2.13
|
||||
.RB "$ " "./a.out 1 10000 100"
|
||||
============ Before allocating blocks ============
|
||||
<malloc version="1">
|
||||
<heap nr="0">
|
||||
<sizes>
|
||||
</sizes>
|
||||
<total type="fast" count="0" size="0"/>
|
||||
<total type="rest" count="0" size="0"/>
|
||||
<system type="current" size="135168"/>
|
||||
<system type="max" size="135168"/>
|
||||
<aspace type="total" size="135168"/>
|
||||
<aspace type="mprotect" size="135168"/>
|
||||
</heap>
|
||||
<total type="fast" count="0" size="0"/>
|
||||
<total type="rest" count="0" size="0"/>
|
||||
<system type="current" size="135168"/>
|
||||
<system type="max" size="135168"/>
|
||||
<aspace type="total" size="135168"/>
|
||||
<aspace type="mprotect" size="135168"/>
|
||||
</malloc>
|
||||
|
||||
============ After allocating blocks ============
|
||||
<malloc version="1">
|
||||
<heap nr="0">
|
||||
<sizes>
|
||||
</sizes>
|
||||
<total type="fast" count="0" size="0"/>
|
||||
<total type="rest" count="0" size="0"/>
|
||||
<system type="current" size="1081344"/>
|
||||
<system type="max" size="1081344"/>
|
||||
<aspace type="total" size="1081344"/>
|
||||
<aspace type="mprotect" size="1081344"/>
|
||||
</heap>
|
||||
<heap nr="1">
|
||||
<sizes>
|
||||
</sizes>
|
||||
<total type="fast" count="0" size="0"/>
|
||||
<total type="rest" count="0" size="0"/>
|
||||
<system type="current" size="1032192"/>
|
||||
<system type="max" size="1032192"/>
|
||||
<aspace type="total" size="1032192"/>
|
||||
<aspace type="mprotect" size="1032192"/>
|
||||
</heap>
|
||||
<total type="fast" count="0" size="0"/>
|
||||
<total type="rest" count="0" size="0"/>
|
||||
<system type="current" size="2113536"/>
|
||||
<system type="max" size="2113536"/>
|
||||
<aspace type="total" size="2113536"/>
|
||||
<aspace type="mprotect" size="2113536"/>
|
||||
</malloc>
|
||||
.fi
|
||||
.in
|
||||
.SS Program source
|
||||
.nf
|
||||
|
||||
#include <unistd.h>
|
||||
#include <stdlib.h>
|
||||
#include <pthread.h>
|
||||
#include <malloc.h>
|
||||
#include <errno.h>
|
||||
|
||||
static size_t blockSize;
|
||||
static int numThreads, numBlocks;
|
||||
|
||||
#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \\
|
||||
} while (0)
|
||||
|
||||
static void *
|
||||
thread_func(void *arg)
|
||||
{
|
||||
int j;
|
||||
int tn = (int) arg;
|
||||
|
||||
/* The multiplier \(aq(2 + tn)\(aq ensures that each thread (including
|
||||
the main thread) allocates a different amount of memory */
|
||||
|
||||
for (j = 0; j < numBlocks; j++)
|
||||
if (malloc(blockSize * (2 + tn)) == NULL)
|
||||
errExit("malloc\-thread");
|
||||
|
||||
sleep(100); /* Sleep until main thread terminates */
|
||||
return NULL;
|
||||
}
|
||||
|
||||
int
|
||||
main(int argc, char *argv[])
|
||||
{
|
||||
int j, tn, sleepTime;
|
||||
pthread_t *thr;
|
||||
|
||||
if (argc < 4) {
|
||||
fprintf(stderr,
|
||||
"%s num\-threads num\-blocks block\-size [sleep\-time]\\n",
|
||||
argv[0]);
|
||||
exit(EXIT_FAILURE);
|
||||
}
|
||||
|
||||
numThreads = atoi(argv[1]);
|
||||
numBlocks = atoi(argv[2]);
|
||||
blockSize = atoi(argv[3]);
|
||||
sleepTime = (argc > 4) ? atoi(argv[4]) : 0;
|
||||
|
||||
thr = calloc(numThreads, sizeof(pthread_t));
|
||||
if (thr == NULL)
|
||||
errExit("calloc");
|
||||
|
||||
printf("============ Before allocating blocks ============\\n");
|
||||
malloc_info(0, stdout);
|
||||
|
||||
/* Create threads that allocate different amounts of memory */
|
||||
|
||||
for (tn = 0; tn < numThreads; tn++) {
|
||||
errno = pthread_create(&thr[tn], NULL, thread_func,
|
||||
(void *) tn);
|
||||
if (errno != 0)
|
||||
errExit("pthread_create");
|
||||
|
||||
/* If we add a sleep interval after the start\-up of each
|
||||
thread, the threads likely won\(aqt contend for malloc
|
||||
mutexes, and therefore additional arenas won\(aqt be
|
||||
allocated (see malloc(3)). */
|
||||
|
||||
if (sleepTime > 0)
|
||||
sleep(sleepTime);
|
||||
}
|
||||
|
||||
/* The main thread also allocates some memory */
|
||||
|
||||
for (j = 0; j < numBlocks; j++)
|
||||
if (malloc(blockSize) == NULL)
|
||||
errExit("malloc");
|
||||
|
||||
sleep(2); /* Give all threads a chance to
|
||||
complete allocations */
|
||||
|
||||
printf("\\n============ After allocating blocks ============\\n");
|
||||
malloc_info(0, stdout);
|
||||
|
||||
exit(EXIT_SUCCESS);
|
||||
}
|
||||
.fi
|
||||
.SH SEE ALSO
|
||||
.BR fmemopen (3),
|
||||
.BR mallinfo (3),
|
||||
.BR malloc (3),
|
||||
.BR malloc_stats (3),
|
||||
.BR mallopt (3)
|
Loading…
Reference in New Issue